UCLA

Recent advances in engineering and technology have led to an unprecedented increase in the demand for high-speed communication links. Carrier signals in the mm-wave (30 GHz to 300 GHz) and THz frequencies (100 GHz to 30 THz) can support large bandwidths, making the mm-wave/THz spectrum a strong contender for deploying ultra-high-speed communication systems. Due to the availability of high fmax transistors in recent silicon and SiGe processes, it is now possible to design cost-effective high-performance integrated circuits in the mm-wave/THz frequency range.

Amplifiers play a crucial role in any electronic system. Designing amplifiers in the mm-wave/ THz spectrum poses some unique challenges compared to amplifier design for RF and lower microwave applications. Low-frequency instability and common-mode oscillations are commonly observed when designing differential amplifiers at mm-wave/THz frequencies. This thesis discusses some of the most common sources of common-mode oscillations and summarizes techniques to ensure stability. Later, a 75 GHz broadband low-noise amplifier in a 90nm SiGe BiCMOS process is presented as a design example. The simulation results verify that stable operation is maintained while achieving the desired performance.